Radomes are used to protect antennas and associated equipment from environmental damage. Particularly, a purpose of structurally thick radomes is to protect expensive or mission-critical radar equipment from environmental damage (for example, wind-blown debris, hail, tree strikes, bird strikes, or even from ballistic fire or shrapnel), thus allowing the radar to continue to operate. The radar systems are reliant on the radio frequency (RF) transmissiveness of the radome. However, stopping environmental threats may damage the radome and introduce localized RF losses. As a result, depending on the nature and/or extent of the radome damage, the radar may have degraded performance over a portion of its field of regard.
Existing methods of detecting damage to radomes include the use of radar interrogation of the radome to find damage, thus requiring the use of additional RF equipment. Some examples use external RF equipment to analyze the radome. Other examples for in-situ testing use additional out-of-band radars to detect damage to the radome. These methods require image-based processing and similar RF analysis algorithms as are used to process the in-band radar signals.
A presently preferred method of detecting radome damage is to use embedded optical fibers coupled with optical interferometric processing to attempt to detect structural deformations of thin composite radomes. This approach is costly and does not address detection of point damage on structurally thick radomes, which do not deflect or deform in a manner similar to thin composite radomes.